US6608803B2 - Recording medium reproduction apparatus - Google Patents

Abstract

The present invention provides a recording medium reproduction apparatus that can continuously reproduce different tunes from recording media at the same numbers of beat and the same beat timing. The recording medium reproduction apparatus includes: a first recording medium reproduction unit; a second recording medium reproduction unit; and a control unit that compares the number of beats per unit time of a tune reproduced from a first recording medium with the number of beats per unit time of a tune reproduced from a second recording medium, and adjusts the reproduction rate of the second recording medium reproduction unit so that the number of beats per unit time of the second recording medium reproduction unit becomes equal to the number of beats per unit time of the first recording medium reproduction unit. With this recording medium reproduction apparatus, any two different tunes to be reproduced from recording media can be adjusted to have the same number of beats and thus reproduced without intermission.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to recording medium reproduction apparatuses, and, more particularly, to a recording medium reproduction apparatus that has a special reproduction function for remixing music recorded on a recording medium, such as a CD player.

2. Description of the Related Art

Conventionally, record players have been used in places like discotheques, where people enjoy dancing to music. Normally, two record players are used at the same time so as not to allow any intermission between tunes. However, in a case where two tunes having different numbers of beats are to be played, there will be an unnatural intermission between the tunes, casting a damper on the pleasure of dancing.

To avoid such a problem, those who handle sound equipment, i.e., disk jockeys, memorize the number of beats of each tune in advance, and then select records in such a replay order that natural reproduction of tunes can be achieved. In order to count the number of beats of a tune, it is necessary to detect a BPM (beat per minute). A disk jockey replays each tune in advance, so as to count the number of beats by tapping in time with the beats.

A natural transition from one tune to another can be achieved by matching the beat timing of the two tunes. Therefore, a disk jockey listens to each tune carefully so as to start replaying the tune at the same beat timing as the previous tune.

However, the above operations, such as the beat detection and beat matching, require a great power of attention and patience, as well as a talent as a disk jockey. As a result, it has been extremely difficult for a general user to perform continuous replay of tunes having different beat timings.

Furthermore, the beat timing matching operation described above is conventionally performed with record players, not with compact disk players and other recording medium reproduction apparatuses. Except for record players, there has been no recording medium reproduction apparatuses that are provided with a beat timing matching function for continuous reproduction.

SUMMARY OF THE INVENTION

A general object of the present invention is to provide recording medium reproduction apparatuses in which the above disadvantages are eliminated.

A more specific object of the present invention is to provide a recording medium reproduction apparatus that can continuously replay tunes having different beat numbers and beat timings reproduced from recording media.

The above objects of the present invention are achieved by a recording medium reproduction apparatus, comprising: a first recording medium reproduction unit; a second recording medium reproduction unit; and a control unit that compares the number of beats per unit time of a tune reproduced from a first recording medium with the number of beats per unit time of a tune reproduced from a second recording medium, and adjusts the reproduction rate of the second recording medium reproduction unit so that the number of beats per unit time of the second recording medium reproduction unit becomes equal to the number of beats per unit time of the first recording medium reproduction unit.

With this recording medium reproduction apparatus, the reproduction rate of the second recording medium reproduction unit is adjusted so that the number of beats at the second recording medium reproduction unit becomes equal to the number of beats at the first recording medium reproduction unit, as described above. Thus, any two tunes having different numbers of beats can be continuously reproduced from recording media.

In the above recording medium reproduction apparatus:

the first recording medium reproduction unit includes a first beat detector that detects beats of a tune being reproduced from the first recording medium;

the second recording medium reproduction unit includes a second beat detector that detects beats of a tune being reproduced from the second recording medium; and

the control unit adjusts the reproduction rate of the second recording medium reproduction unit so that a beat detecting timing of the second beat detector becomes equal to a beat detecting timing of the first beat detector.

As described above, the reproduction rate of the second recording medium reproduction unit is adjusted so that the beat detecting timing of the second beat detector becomes equal to the beat detecting timing of the first beat detector. Thus, any two different tunes can be continuously reproduced from recording media at the same beat timing.

The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one embodiment of a recording medium reproduction apparatus of the present invention;

FIG. 2 is a block diagram showing the functions of a data maintenance DSP shown in FIG. 1;

FIG. 3 is a block diagram showing the functions of a CD sound effect DSP and a sampler effect DSP shown in FIG. 1;

FIG. 4 is a plan view of controller units of a pair of recording medium reproduction apparatuses of the present invention;

FIG. 5 shows the structure of a display shown in FIG. 4;

FIG. 6 is a block diagram of a BPM function shown in FIG. 3;

FIGS. 7A and 7B are signal waveform charts illustrating an operation by the BPM function;

FIG. 8 is a flowchart of a beat synchronization control process of the present invention; and

FIG. 9 is a flowchart of the beat synchronization control process that continues from FIG.8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is a description of embodiments of the present invention, with reference to the accompanying drawings.

FIG. 1 is a block diagram of one embodiment of a recording medium reproduction apparatus of the present invention. In this figure, aCD reproduction unit10 rotationally drives a compact disk (CD) that is a recording medium at a reproduction rate twice as high as a normal reproduction rate (double rate). A reproduction signal reproduced by a pickup of theCD reproduction unit10 is supplied to a CD reproduction digital signal processor (DSP) in theCD reproduction unit10 via an RF amplifier. In the CD reproduction DSP, a signal processing operation, such as an EFM (eight-to-fourteen modulation) operation or a CIRC (cross-interleave Reed-Solomon code) decoding operation, is performed on the reproduction signal.

A sub code is extracted and separated from the reproduction signal, and a decoding operation is performed on the sub code. The sub code data is stored in the RAM in amain microcomputer12, in accordance with a counter signal supplied from themain microcomputer12. The audio data processed by the CD reproduction DSP is supplied to adata maintenance DSP14.

Thedata maintenance DSP14 is connected to a DRAM (dynamic RAM)16 for storing the audio data. Here, the data maintenance DSP14 serves as a memory controller. TheDRAM16 stores the supplied audio data for ten seconds for instance, and serves to realize various functions, such as an anti-shock function for providing protection when a sound jump is caused due to a defect in the audio data, a quick start function for instantly starting a desired tune, a seamless loop function for repeatedly reproducing the audio data between predetermined two points, a scratch function, a function for changing the tempo of each tune, and a brake function for gradually reducing the reproduction rate and then stopping the reproduction.

The data maintenance DSP14 writes audio data read out at a double rate into theDRAM16 in accordance with the counter signal supplied from themain microcomputer12. At the same time, the data maintenance DSP14 reads out audio data at a single rate in accordance with the counter signal supplied from themain microcomputer12, and supplies the read audio data to a CDsound effect DSP18.

The CD sound effect DSP18 is connected to awork memory DRAM20, and performs various effect adjustment operations, such as key adjustment, output level adjustment, and voice reduction for reducing only the volume of the vocal part of a tune. The audio data outputted from the DSP18 is supplied to a D/A converter22 via a digital filter, and also to a sampler effect DSP26.

The sampler effect DSP26 is connected to adata storage DRAM28, and serves as a memory controller. TheDRAM28 is capable of storing audio data for ten seconds, for instance. The sampler effect DSP26 performs a sampler operation. More specifically, the audio data picked up during a period between a sampling start point and a sampling end point designated by user is stored in theDRAM28. The stored audio data is read out at a reproduction timing that is also determined by the user, and then supplied to a D/A converter30 and theDSP18. The DSP18 mixes its own output audio data with the audio data from theDSP26, and then supplies the resultant mixture of audio data to a D/A converter22.

Themain microcomputer12 is connected to an EPROM (erasable programmable ROM)32 in which programs and data used for performing operations are stored, and to an EEPROM (electric erasable programmable ROM)34 in which various setting values, such as tempo values and loop points, are stored for each tune (or each track). Aclock generator36 generates a clock signal, and supplies the clock signal to theCD reproduction unit10 and themain microcomputer12.

Themain microcomputer12 also reads out a sub code from a built-in RAM in accordance with the counter signal, and supplies the sub code to amicrocomputer42 in acontroller unit40. Themicrocomputer42 converts the sub code into a time code, and displays the time code on adisplay unit44. Thecontroller unit40 includes anoperation unit46 that has various operation keys for users to handle, and is connected to themicrocomputer42.

FIGS. 2 and 3 are block diagrams showing the functions of theDSPs14,18, and26. As shown in FIG. 2, a comparison andconnection function50 of theDSP14 compares audio data read out at the double rate with the last data stored in theDRAM16, in accordance with the counter signal supplied from themain microcomputer12. After the comparison, the read audio data is connected to the last data in theDRAM16. Amemory write function51 writes the connected audio data into theDRAM16. A memory readfunction52 reads out audio data from theDRAM16. Atempo function54 changes the read rate of the memory readfunction52, thereby adjusting the tempo. A fade-in/fade-out function55 adjusts the level of audio data at a time of fade-in or fade-out.

In FIG. 3, ade-emphasis function60 of theDSP18 carries out a de-emphasis operation for canceling emphasis at the time of CD recording. Akey adjustment function61 changes the keys while fixing the tempo. A BPM (beats per minute) function62 counts the number of beats per minute in each tune. Avoice reduction function63 reduces the volume of the vocal part of each tune. An outputlevel adjustment function64 adjusts the output level. The audio data outputted from the outputlevel adjustment function64 is outputted via amixing function65, and supplied to asampler function67 in theDSP26 when aswitch66 is on.

Thesampler function67 writes audio data into theDRAM28, and reads out audio data from theDRAM28 when aswitch70 is on. Atempo function68 adjusts the tempo of the audio data supplied from thesampler function67. Akey adjustment function69 changes the keys while fixing the tempo. The audio data outputted from thekey adjustment function69 is outputted via theswitch70, and supplied to the mixingfunction65 via aswitch71 that is switched on with theswitch70. In the mixingfunction65, the audio data outputted from thekey adjustment function69 is mixed with the audio data outputted from the output level adjustment function, and the mixed audio data is outputted from the mixingfunction65.

It should be understood that the recording medium reproduction apparatus shown in FIG. 1 is used in pairs, and themain microcomputer12 of each of the recording medium reproduction apparatuses transmits and receives information to and from each other. FIG. 4 is a plan view of thecontroller units40 of a pair of recording medium reproduction apparatus. Since both of thecontroller units40 have the same structure, reference numerals are allotted to only one of thecontroller units40 in FIG.4.

In FIG. 4, adisplay80 of thedisplay unit44 displays various information including a track number and a time code, while adisplay81 shows a BPM value. Theoperation unit46 is equipped with a preset key82, ajog dial83, a skip key84, asearch key85, a play/pause key86, abank key87, a memory key88 a recall key89, an enter key90, aTAP key91, aBPM key92, atempo SYNC key93, abeat SYNC key94, aloop key95, an A key96, aB key97, asample key98, an INkey99, an OUT key100, atempo key101, atempo volume indicator102, ascratch key103, abrake key104, a ten key board105, aminus key106, and aplus key107.

FIG. 5 shows thedisplay80 of thedisplay unit44 in greater detail. In FIG. 5, thedisplay80 includes atempo indicator110 for tempo control and akey indicator111 for key control. The values indicated by each of theindicators110 and111 is shown by the percent. The tempo control is carried out by slidably moving thetempo volume102 so as to adjust the tempo, i.e., the reproduction rate, of each tune being reproduced. With a normal reproduction rate being1, the largest possible variable range of the reproduction rate is 32%. As the tempo is changed, the key of the tune being reproduced depending on the temp is changed.

The key control is performed by changing the key of each tune being reproduced while fixing the tempo. There are two adjustment methods: one is to change the key by the predetermined percent, depending on the number of times theminus key106 or theplus key107 is pushed; and the other is to change the key by the half, depending on the number of times theminus key106 or theplus key107 is pushed.

FIG. 6 is a block diagram of theBPM function62 shown in FIG.3. In FIG. 6, a low-pass filter120 selectively lets only a low-frequency component, such as the sound of bass drum, among audio data supplied from thede-emphasis function60. In alevel comparator121, the low-frequency component of the waveform shown by the solid line in FIG. 7A is compared with a set detection level shown by the broken line in FIG.7. In accordance with the comparison result, apulse output unit122 generates a beat pulse and supplies the beat pulse to themain microcomputer12. The beat pulse is high (“1”) when the low-frequency component exceeds the set detection level, and is low (“0”) when the low-frequency component is lower than the set detection level, as shown in FIG.7B. In FIG. 7A, half-wave rectification has been performed on the frequency component. In a DSP, however, the number of beats is detected depending on the set detection bits in the PCM data.

Themain microcomputer12 measures the cycles of the rise and fall of the beat pulse. In some tunes, the rhythm beaten by a pass drum is not necessarily monotonous, but there might be several rhythm patterns. Therefore, themain microcomputer12 converts the beat cycles into the number of beats. If the number of beats is in the range of 81 to 161 per minute, the number of beats is employed as the BPM value. The BPM values thus obtained for the last few times are then averaged, and the average value is displayed on thedisplay81.

In this embodiment, one of the recording medium reproduction apparatus shown in FIG. 4 is a master player while the other one is a slave player. The master player reproduces a first tune, and the slave player reproduces a second tune that follows the first tune without intermission.

FIGS. 8 and 9 are a flowchart of a beat synchronization control operation. In FIG. 8, in step S10, the beat pulse and the BPM value X of a tune being currently reproduced by the master player are detected. In step S12, a tune to be reproduced after the currently reproduced tune is reproduced by the slave player so as to detect the beat pulse and the BPM value Y. The detected BPM values X and Y are displayed on thedisplays81 of the master player and the slave player, respectively. In step S14, the beat SYNC key94 or thetempo SYNC key93 of the slave player is switched on.

In step S16, the BPM value X of the currently reproduced tune detected by themain microcomputer12 of the master player is transferred to themain microcomputer12 of the slave player. In step S18, themain microcomputer12 then calculates the ratio of the BPM value X of the tune being currently reproduced by the master player to the BPM value Y to be next reproduced without intermission by the slave player.

In step S20, themicrocomputer12 of the slave player multiplies the above ratio (X/Y) by the tempo value of the slave player (already converted into an actual number from the number in percent), so that the tune to follow the currently reproduced tune is reproduced at the obtained tempo value. Thus, the tempo of the tune to be continuously reproduced is matched to the tempo of the tune reproduced by the master player. By doing so, the BPM value Y of the tune to be continuously reproduced is matched to the BPM value X of the currently reproduced tune. In step S21, if it is determined that thetempo SYNC key93 is on, a lamp built in thetempo SYNC key93 for indicating tempo synchronization is switched on in step S23. After thetempo SYNC key93 is switched on, the operation comes to an end. If thebeat SYNC key94 is switched on in step S14, the operation moves to a beat synchronization operation in step S22 and the following steps.

In step S22, themain microcomputer12 of the slave player compares the beat pulse transferred from the master player with the beat pulse of the slave player. In step S24 of FIG. 9, themain microcomputer12 of the slave player determines whether or not the time difference between the rising times of the beat pulses of the main player and the slave player is within the range of ±20% of a beat cycle that is an inverse number of the BPM value Y of the tune to be continuously reproduced.

If the time difference is beyond the range of ±20%, the operation moves on to step S26, in which themain microcomputer12 of the slave player determines whether or not the rising time of the beat pulse of the slave player lags behind. If the rising time of the beat pulse of the slave player lags behind, the operation moves on to step S28, in which themain microcomputer12 of the slave player temporarily increases the tempo of the tune to be continuously reproduced by a predetermined amount (8%, for instance), thereby approximating the rise time of the beat pulse of the tune to be continuously reproduced to the rise time of the beat pulse transferred from the master player. The operation then returns to step S24.

Meanwhile, if the rise time of the beat pulse of the slave player is ahead of time, the operation moves on to step S30, in which themain microcomputer12 of the slave player reduces the tempo of the tune to be continuously reproduced by a predetermined amount (8%, for instance), thereby approximating the rise time of the beat pulse of the tune to be continuously reproduced to the rise time of the beat pulse transferred from the master player. The operation then returns to step S24.

If the time difference is determined to be within the range of ±20% in step S24, the operation moves onto step S32, in which themicrocomputer12 of the slave player fixes (locks) the tempo of the tune to be continuously reproduced, because the tune will sound natural to users. In step S34, the lamp built in thebeat SYNC key94 is switched on to indicate the beat synchronization between the tune being currently reproduced by the master player and the tune to be continuously reproduced by the slave player. The operation then returns to step S24.

Although the master player and the slave player automatically detect the BPM values in this embodiment, it is also possible to manually input the BPM values withTAP keys91 on the master player and the slave player, respectively. A user can press the tap key91 in time with a tune while listening to the tune. In such a case, the number of times theTAP key91 is switched on in a predetermined period of time (12 seconds, for instance) from the first time when theTAP key91 is switched on is counted. The counted value is then converted into a PBM value and displayed on eachdisplay81 of the master player and the slave player. At the same time, the cycles of tapping the Tap key of the master player are used as the beat pulse.

Although CDs are used as recording media, it is of course possible to use DVDs (Digital Versatile Disks) and MDs (Mini Disks) as recording media.

The present invention is not limited to the specifically disclosed embodiments, but variations and modifications may be made without departing from the scope of the present invention.

The present application is based on Japanese priority application No. 2000-050082, filed on Feb. 25, 2000, the entire contents of which are hereby incorporated by reference.

Claims (2)

What is claimed is:

1. A recording medium reproduction apparatus, comprising:

a first recording medium reproduction unit;

a second recording medium reproduction unit; and

a control unit that compares the number of beats per unit time of a tune reproduced from a first recording medium with the number of beats per unit time of a tune reproduced from a second recording medium, and adjusts a reproduction rate of the second recording medium reproduction unit so that the number of beats per unit time of the second recording medium reproduction unit becomes equal to the number of beats per unit time of the first recording medium reproduction unit.

2. The recording medium reproduction apparatus as claimed inclaim 1, wherein:

the first recording medium reproduction unit includes a first beat detector that detects beats of a tune being reproduced from the first recording medium;

the second recording medium reproduction unit includes a second beat detector that detects beats of a tune being reproduced from the second recording medium; and

the control unit adjusts the reproduction rate of the second recording medium reproduction unit so that a beat detecting timing of the second beat detector becomes equal to a beat detecting timing of the first beat detector.

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